Precision alignment of large power gear drives, such as for a telescope or antenna, typically requires three independent adjustments, one translation and two angular, to achieve full tooth contact and suitable backlash. Achieving the full capacity of a gear drive often requires milli-inch precision in the lead (helix) contact alignment, for each direction of rotation. Precision alignments are sometimes done by shimming between the foundation and the pinion gear housing. The radial adjustments are made using shims of different thicknesses to adjust the backlash (gaps) between the mating teeth. Lead or tilt adjustments can be made using tapered shims to tilt the pinion gear housing. Other designs have used an eccentric sleeve to permit center-to-center spacing adjustment to adjust backlash. Tilt adjustments can also be made by tilting a baseplate with jackscrews, then welding across the gaps between the baseplate and structure beneath.
Reference will now be made to the exemplary embodiments illustrated, and specific language will be used herein to describe the same. It will nevertheless be understood that no limitation of the scope of the invention is thereby intended.